Diesel fuel oil



Patented Apr. 2, 1946 UNITED STATES PATENT OFFICE cellus T. Flaxman, Inglewood, Calif., to Union Oil Company of California,

assigns;

Los An geles, Calif., a corporation of California No Drawing. Application October 17, 1941,

- Serial No. 415,406

' '3 Claims.

This invention relates primarily to fuels for Diesel engines and the like.

Recent productions of Diesel fuels have involved heavy treatment of the Diesel fuel stocks to produce highly refined fuels having high octane rating and relative freedom from objectionable odors, as distinguished from earlier Diesel fuels of objectionably low cetane number and -bad odor. It has been discovered that in accomplishing these advantages, the heavy treatment has removed from the fuel constituents which heretofore apparently have imparted lubricating qualities whereby the fuel itself lubricated the moving parts of the injectors used in feeding the Diesel fuel to Diesel engines. Low viscosity fuels have introduced the same lubrication problem.

The particular object of this invention is to produce well refined Diesel engine fuels with high cetane numbers and good odor which at the same time will contain constituents sary lubricating qualities.

Briefly, the present invention resides in a Diesel engine fuel which-has been higlyvreflned to impart desirably high octane numbers, for example a cetane number of 50 orabove, to eliminate substantially all constituents imparting objectionable odors, to which highly refined fuel there has been added high molecular weight organic acids recovered from petroleum fractions, and more particularly those obtained from fractions similar to the Diesel fuel itself, or by pre-treatment of the Diesel fuel itself, which heavy acidic fractions impart adequate lubricatin properties.

In practicing the invention the Diesel fuel is produced by any well known or preferred refining method to yield a product of good odor, as indicated, and having a desirably high octane number in the order of 50 to 65. Such a Diesel fuel may, for example, be prepared by the recognized refinery procedure of fractional distillation to obtain the desired boiling'range, with subsequent solvent treatment of' the correct boiling range material, or by the solvent treatment of 'a wide boiling range cut and the subsequent redistillation and fractionation to the desired boiling range, or by any procedure recognized in the art for the preparationof such a Diesel fuel. These fuels are of the generally well known types.

Having obtained the Diesel fuel of desired reilnement, there is added to the fuel a small quan. tity in the order of 0.01% to 0.50% of the above mentioned high molecular weight organic acidic material obtained from Diesel fuel itself or kin-' dred fractions.

This additive material, which is adapted to restore to the Diesel fuel at least sufflcient of the lubricating qualities removed by the heavy treatment, and to impart lubricating values to low viscosity fuels, may be prepared as follows.

A Diesel fuel stock, otherwise ready for use as presenting necesor the like), is treated with a caustic wash, such as a aqueous solution of sodium hydroxide.

The purpose of this wash is to remove from the I said petroleum fraction various acidic materials of organic character which are neutralized by the caustic. These acidic materials include naphthenic acids of lower and higher molecular weights and other organic acids which may include fatty acids, acids of cyclic structure and the like. By the caustic wash, said naphthenic acids are neutralized to produce sodium soaps thereof which are removed from the petroleum fractions inthe aqueous solution. The caustic soap solution is then neutralized in a wellunderstood' man ,ner with a strong mineral acid such as sulfuric acid, for the purpose of "cracking" the soaps and liberating the organic acids. The latter being lighter than the aqueous solution rise to the surface and are separated. I

In order to separate the lighter naphthenic acids from the heavier organic acids, these cracked-out and separated acids are distilled whereby to drive the lighter naphth'enic acids overhead. This overhead naphthenic acid product is liquid at normal temperatures in the case of materials obtained .from Diesel fuel, kerosene, stove oil and the like. The distillation normally takes place under 29' inches of mercury vacuum 30 and at atemperature of about 150 F. to 550 F. The naphthenic acid comes off as a side out at about 350 F. Theacids so driven over possess an over-all acid number of about 235, and variously possess molecular weights ranging from s about 170 to 400 (average about 240) or from about 10 carbons to 20 carbons per molecule (average about 15 carbons) Having distilled on the desired naphthenic the preferred additive material according to the present invention. These "bottoms are solid or semi-solid at normal room temperature, and have an over-all acid number of about 140. They are soluble in petroleum fractions in the Dieselfuel range and in all lubricating oil fractions. These bottoms possess other characteristics as follows:

Viscosity, Saybolt llniversal at 210 F.

. seconds 157 Color N. P. A Dark Conradson carbon value 1.88 Boiling range of bottoms:

' Initial 5% 10% 20% 541.F. 632 F. 643 F. 656 F.

- Flash point 0. o. 0---. .21 1. 400 Fire point C. O. C' 470 GravityA. P. I 12.1 Specific gravity 0.9855

Acid number 'mg. KOH per gm 1 acids, a quantity of bottoms" remains, which is type possibly satisfactory manner,

to perhaps as low may be used, but tional practical advantage although greater percentages of these bottoms character often fail The chemical constitution of these bottoms is not well understood. They probably contain considerable proportions of high molecular weight naphthenic acid which like the mass as a whole are not freely liquid at normal temperatures. Also they probably contain high molecular weight acids of the aliphatic series (possibly some unsaturated as well as a majority of saturated acids),-and, in addition to naphthenic acids, cyclic acids of the six carbon ring both saturated and unsaturated. The above described bottoms meet all the requirements for the present invention in a highly when added in the range of 0.01% to 0.50% to Diesel fuel of a hight degree of refinement such as above indicated, or

of low viscosity. The average quantity of the bottoms employed will be in the order of 0.10%. Smaller quantities with lesser effects range down as 0.03%. Higher percentages there appears to be no addiabove about 0.25%,

up to about 0.50% do not appear to have any objectional effect.

As an exam le of the effectiveness of this material when added to a highly refined Diesel fuel of high cetane number as described, Diesel engines have been found to continue through toward the intended maximum life of the injectors (which is the intended life of the engine) long after the same high y refined or low viscosity fuel without the additive material has caused injectors to fail for want of lubrication. For example, the life of a good. Diesel engine may be set at more than one hundred thousand miles of vehicle travel. The out added lubricating constituents of suitable at around thirty-five thousand miles or. so.

By employment of about 0.10% of the above described bottoms as an additive, the injectors have continued without failure to mileages in excess of fifty thousand miles even where the unmodified fuel had been used in the engine up to around or a little overtwenty-five thousand miles.

highly refined fuels with- 1 in a Diesel engine is not to be confused with the addition of naphthenic acids to an ordinary lubricating oil as disclosed by the Wells and Southcombe Patent 1,319,129. In the present case we are dealing with injector parts constructed with very small clearances which require liquids of very low viscosity (maximum viscosity of 40 seconds at 100 F. S. U.), which is an entirely different problem from improving the properties of a typical lubricating oil.

Not only do the present additives, especially the preferred bottoms, act to impart necessary lubricating qualities to highly refined Diesel fuels, but there are evidences that these materials also impart certain detergent properties so that certain types of Diesel engines which are characteristically dirty, in that they accum late deposits about the injector tips and elsewhere, become much cleaner and freer from deposits when using the present fuel.

The additive materials ofthe present invention are useful both the other indicated advantages. Where the acidic materials are obtainable from other petroleum fractions, such as gas oils and possibly somewhat heavier oils, they also maybe employed, as will be apparent to those skilled in the art.

We claim:

1. A Diesel fuel containing in the order of 0.01% to 0.5% of a high molecular weight organic acidic material obtained from petroleum fractions by caustic treatment thereof and recovered as a heavy normally solid to semi-solid bottoms fractionby distilling over thenic acid components.

2. A Diesel fuel containing a minor proportion sumcient to impart lubricating properties to a highly refined Diesel fuel otherwise deficient in lubricating properties, of high molecular weight organic acidic materials comprising naphthenic acids obtained as a bottoms component derived from distilling over the naphthenic acids contain- We have also found that, in addition to using the highly preferable acidic bottoms above de scribed, it is possible to obtain some appreciable advantage by employing as an additive the overhead naphthenic acid distillate described. The percentage of these acids will beapproximately in the same order as that of the bottoms when employed. Under these circumstances we find that even these naphthenic acids are non-corrosive in the engine, as is also true of said bottoms. This distinguishes sharply from the use of the other types of organic acids, such as oleic acid, which are corrosive inthe Diesel engine, both with respect to the injectors and otherwise. Even though these naphthenic acids are not to be considered as-full equivalents of the -carbons per molecule and ing up to about 20 the organic acidic materials obtained in the refining of Diesel fuel, kerosene fractions and similar petroleum fractions by caustic treatment.

3. A method for the production of Diesel fuels comprising producing a well refined Diesel fuel otherwise deficient in lubricating values, treating a petroleum fraction with an aqueous caustic wash to remove therefrom the organic acidic material matter contained in the petroleum fraction, separating the resultant soaps from the petroleum fraction, treating said soaps with a strong mineral acid to liberate the organic acids, distilling the liberated organic acids to divide them into a naphthenic acid overhead component comprising naphthenic acids having .up to about 20 a bottoms component and returning a minor proportion of said bottoms component to said fuel to impart suflicient lubricating properties.

BENJAMIN T. ANDERSON.

MARCELLUS T. FLAXMAN.

in addition to the normally liquid naphcarbons per molecule from 

